Interpretive Summary: Potato is a valuable source of potassium in the human diet and contributes to enhanced health in most people. However, individuals with compromised kidney function must minimize their potassium intake. There are no published reports on the effectiveness of commonly recommended methods to reduce potassium levels in potatoes. This study was undertaken to determine the effects of leaching and boiling on levels of potassium and other minerals in potato tubers. In addition, mineral levels in major potato cultivars are reported. Leaching alone did not significantly reduce levels of potassium or other minerals in tubers. Boiling tuber cubes and shredded tubers decreased potassium levels by 50% and 75%, respectively. Reductions in mineral levels following boiling were observed for several minerals, including phosphorus, magnesium, sulfur, zinc, manganese and iron. Boiling did not consistently decrease calcium, boron and copper levels. There was no difference between the leaching plus boiling and boiling alone. Differences in mineral levels were detected among cultivars, but they were too small to be nutritionally important. People who wish to eat potatoes as a source of minerals should boil them whole or bake, roast, or microwave them. Those who must reduce potassium uptake should boil small pieces before consuming them.

Technical Abstract:
The white potato (Solanum tuberosum L.) is a valuable source of potassium in the human diet. While most consumers benefit from high levels of potassium in potato tubers, individuals with compromised kidney function must minimize their potassium intake. This study was undertaken to determine the effects of leaching and boiling on levels of potassium and other minerals in potato tubers. In addition, mineral levels in tubers of six North American potato cultivars are reported. Leaching alone did not significantly reduce levels of potassium or other minerals in tubers. Boiling tuber cubes and shredded tubers decreased potassium levels by 50% and 75%, respectively. Reductions in mineral levels following boiling were observed for phosphorus, magnesium, sulfur, zinc, manganese and iron levels. The boiling treatment did not consistently decrease calcium, boron and copper levels. There was no difference between the leaching plus boiling treatment and the boiling treatment. Significant differences in mineral levels were detected among cultivars, but they were too small to be nutritionally important. Individuals wishing to maximize the mineral nutrition benefits of consuming potatoes should boil them whole or bake, roast, or microwave them. Those who must reduce potassium uptake should boil small pieces before consuming them.